Justification:
The native populations (Black, Caspian and Aral Sea basins) are slowly but continuously declining due to river regulation. Also hybridisation with domesticated introduced stocks, East Asian congeners and their hybrids, is a serious long term threat for the species. However, superficially pure carp (currently it is impossible to identify pure carp by genetic analysis) are still abundant in the lower parts of rivers within its native range. Most likely, only very few stocks remain "genetically unpolluted" as a result of this long lasting process. The average age of the spawners is estimated to be between 20-25 years, as they are a long lived species (up to 50 years). Although no population data exists, it is suspected that in the past 60 to 75 years within the species native range, river regulation (due to channelization and dams), which impacts the species as they need flooded areas at very specific times to successfully spawn, and hybridisation with introduced stock, has caused a population decline of over 30%.

Black, Caspian and Aral Sea basins. Introduced throughout the world. Cultivated in large quantities for human food and stocked for sport fishing.

In Europe, C. carpio has apparently been domesticated since the Middle Ages and cultivated stocks are assumed to be derived from the wild form of the Danube. Wild stocks occur naturally only in rivers draining to the Black, Caspian and Aral Seas. C. carpio is widely cultivated worldwide, but in fact many cultivated stocks (and most of the Asian ones) belong to several other East Asian species. One of them, C. rubrofuscus (often erroneously referred to as C. carpio haematopterus) is cultivated in several eastern European countries and has been introduced to Russia and Ukraine. It is not known whether it has become established there. In western Europe, Japanese ornamental varieties (kois) possibly derived from C. rubrofuscus or of hybrid origin occasionally escape from ponds. Wild C. rubrofuscus are distinguished from wild C. carpio by having 29-33 + 2-3 lateral line scales (vs. 33-37 + 2-3), 18-22½ branched dorsal rays (vs. 17-20½), body silvery with red pelvic, anal and lower caudal lobe (vs. grey to bronze).

Habitat: Warm, deep, slow-flowing and still waters, such as lowland rivers and large, well vegetated lakes. Introduced in all types of water bodies. Spawns along shores or in backwaters. Successful survival of larvae only in very warm water, among shallow submerged vegetation.

Biology: Males reproduce for the first time at 3-5 years, females at 4-6. Lives up to 50 years and usually spawns every year. Age of maturity is related to latitude and altitude. Spawns in May-June at temperatures above 18°C. Adults often make considerable spawning migrations to suitable backwaters and flooded meadows. Individual females spawn with a few males in dense vegetation. The sticky eggs are attached to water plants or other submerged objects. Larvae and juveniles inhabit warm and shallow flooded river margins or backwaters, feeding mostly on very small zooplankton (rotifers). Reproductive success is restricted to years when the water level starts rising in May and when high temperatures and flooding of terrestrial vegetation last for a long period during May and June. Juveniles and adults feeds on a wide variety of benthic organisms and plant material. Most active during dusk and dawn. Very tolerant of low oxygen concentrations.